Multiple unit sound amplifier



Filed April 6, 1927 C D HAIGES MULTIPLE UNIT SOUND AMPLIFIER AMPLIFIEI?Patented Mar. 15, 1932 narra STATES PAT CARLETON D. HAGIS, OFHADDONFIELD, NEW JERSEY, ASSIGNOR, BY MESNE AS- SIGNMENTS, T0 RADIOCORPORATION OF AlVIERICA, OF NEW YORK, l'. Y., A CORPORA- TION OF:DELAWARE MULTIPLE UNIT SOUND AMPLIFIER Application filed April 6, 1927.Serial No. 181,486.

This invention relates to the amplification of sound, particularly tomeans for producing relatively large volumes of sound, as in auditoriumand lield Work, although certain features of the invention areapplicable to the amplification of sound in volume suitable for therooms of dwellings and the like.

It is an object of this invention to provide improved means forproducing and eiiiciently amplifying sound Without overloading the soundproducing mechanism and Without substantial distortion of the producedsound.

Another object of this invention is to provide improved means foramplifying sound, particularly relatively large volumes of sound, whichis also-directive in character so that it Amay be used in such a Way asto minimize or eliminate the disadvantageous consequences of adjacentsound reflecting surfaces.

Other objects Will appear as the description of the invention proceeds.

The invention is capable of receiving a variety of mechanicalexpressions, one of which has been shown on the accompanying drawings,but itis to be expressly understood that the drawings are for purposesof illustration only and are not to be construed as a definition of thelimits of the invention, reference being had to the appended claims forthat purpose.

Referring in detail to the drawings, Wherein the saine referencecharacters are employed to designate corresponding parts in the severalfigures,

Fig. l is a perspective of an embodiment of the present invention;

Fig. 2 is a fragmentary section, on an enlarged scale, on the line 2 2of Fig. 1;

F ig.' 3 is a section of Fig. 1 taken at right angles to the section ofFig. 2; and

Fig. 4E is a. fragmentary rear elevation on the scale of Fig. 2.

`When relatively large volumes of sound are required, as in auditoriumor field Work, a sound producing unit, such as a loud speaker orelectro-magnetic receiver, of conventional size, cannot be ysuppliedWith suiicient energy to produce the desired volume of sound Withoutoverloading the unit and producing the distortions attendant on suchoverloading. Nor can the size of such a sound producing unit beincreased indelinitely, in order to produce large volumes of sound,Without introducing distortions by reason of the mass and inertiaeffects which are attendant on the use of large vibratory elements.

In conformity with the present invention the desired Volume of sound isobtained by connecting a plurality of electro-magetic receiver or loudspeaker units, preferably in series, each of said units being ofsuitable size and construction to generate sound Waves with a minimumdistortion, and each of said units being supplied with only so muchenergy as can be properly handled Without danger of distortion. Havingdetermined the quantity of sound energy Which can be properly generatedfrom a given unit Without substantial distortion, as many units are em'-ployed as may be necessary to bring the total sound energy up to thedesired amount, and the number of units employed Will thus vary with theuse to which the deviceis to be put. The number of units to be usedhaving been determined sound amplifying and directing means inconformity With the present invention are provided therefor, asillustrated on the drawings, wherein the invention is shown as appliedto the amplification of sound from a plurality of sound productingunits.

These sound producing units, only one of which is sliovvn at l, andwhich may be of any suitable type, size and construction, are preferablymounted in a rovv with their vibratory elements adapted to propagatesound from a common surface, which may be curved or plane as shown, lnthe structure illustrated, the units are mounted with their vibratoryelements in register With, and preferably conforming substantially withthe size of, apertures 2 provided in a bafie 3 supported in any suitableWay, as by an elongated box-like structure d extending rearwardly of thebaiiie 3 and having transverse partie tions 5 extending between the topand bottoni 7 thereof, on which the respective units are mounted in anysuitable Way.

Extending forwardly of the apertured bailie 8 is a trough-shapedamplifier of any suitable size, construction and material, and

shown as composed of curved side walls 8 and 9 and end walls 10 and 11which may beV either plane or curved. The size of the bot'- tom of thetrough or inlet end of the amplifier' is determined by the number andmechanicalimpedance value of the sound producing units employed, itVbeing noted that it is at least as large, and preferably larger, thanthe area ofl the vibratory elements; the size of the mouth of the troughor outlet of the amplifier is determined Vby the intensitykk of thelowfrequencies desired in conformity with principles well understood inthedesion of amplifiers; the flare ofthe amplifier between the Vinletand the outlet is preferably such that the cross sections vary inconformity with' an exponential equation so asfto obtain maxi mumefficiency inthe amplification of the sound waves. Theamplifier ispreferably made of substantially non-vibratory construction, and to thisend its side wallslS and Y 9 are shownas braced with iibs-lyand its endwalls are shown as strengthened by edge strips 13 and ribs 14. It is tobe expressly understood, however, that the amplifier and the supportingframe work for the sound proV ducing unit or units may be built up inany suitable way so as to Vconform with the-use to which the amplifieris to be put and to obtain the desired strength and rigidity tak inginto consideration the materal used, the

size of the parts and the manner of support.

A trough-like amplifier ofthe character illustrated propagates a soundwave having a' substantially regular vand uninterrupted front which isof generally cylindrical form and therefore highly directive incharacter. Advantage is preferably taken of this'fact in so mounting theamplifier in its relation to adjacent sound reflecting surfaces that maybe productive of interferences, dissonances, etc.,- as to minimize theeffect of such surfaces by causing the wave front to expand withthe'aXis ofits cylindrical surface at the proper angularity t'o suchsound reflectingsurfaces. Y p Y Y sound amplifying device embodying thepresenty invention inherently possesses many notable advantages,including that it occupiesonly a relatively small volume of space for adesiredamplification and low frequency cutoff; it is relatively simpleandinexpensive 'in construction; it ali'ords a cut-off which is notsharply limited by the length of the device for a common rate ofexpansion in cross sectional area, whereby the actual cut-off may bemany cycles below that apparently characteristic of an amplifier havingthe outlet area employed; it introduces none of the constructional andacoustic difiiculties inherent in the use of bent and angularly relatedpassages; and it affordsan amplificationthat is productive of a verypleasing sound quality, particularly when employed with the soundproducing unit having an increasing sound output at the lower frequency;and it provides means whichare readily applicable to the amplificationof sound under a wide variety of conditions and of a wide variety ofvolumes.

llt will therefore be perceived that sound Yproducing means, capable ofhandling relatively large volumes of sound energy, have been provided insuch a way vas to eliminate overloading ofthe sound producing units andthe distortion incident Ato theY use of large sound producing units,while at the same time "the desired amplification of the sound generatedby the one or more units is effected in a manner which is highlyeiiicient and which assures the propagation of regular and'uninterrupted wave fronts. YMoreover, the am? plifier is of such acharacter as to be higl'ily directive in character so that the eect ofadjacent sound reflecting surfaces may be minimized. f I Y Y Y Whilertheembodiment of the invention illustrated on the drawings has beendescribed with considerable particularity, it is to be expresslyunderstood that the invention is not to be restricted thereto, as thesame is capable of receiving a variety of mechanitially devoid ofinterior obstructions for amplifying the sound generated by all vof saidunits.

2. 'In a device of the character described, a

series of loud speaker units arranged to gen- Verate sound ina commonsurface, and'common amplifying meanssubstantially devoid V.of interiorobstructions for all of said units.

e 3.' In a device of the character described, a series of loud-speakerunits arranged to generate "sound ina common plane, and com- Vmonamplifying means substantially devoid of interior obstructions for allofsaid units, the cross sectional area of said common amplifying meansbeing not less than the combined area of all of the vibrating elementsof said units.

4. In a device of the characterdescribed, the combination of a series ofreceiver units arranged .substantially in aline and adapted to generatesoundin a common surface, and

a trough-shaped' amplifier which flares from said units to the outletthereof for amplifying sound generated by all of said units, said jamplifier being substantially devoid of interior obstructions.

5. In a device of the character described, the combination of a seriesof loud speaker units arranged in a substantially straight line andadapted to generate sound in a common plane, and a trough-shapedamplifier substantially devoid of interior obstructions for amplifyingthe sound generated by all of said units.

6. In a device of the character described, a series of loud-speakerunits arranged substantially in a line, a box-like cellular structurefor supporting said units and a troughshaped amplifier substantiallydevoid of interior obstructions for amplifying the sound generated byall of said units.

7. In a device of the character described, the combination of anapertured baffle, a series of loud-speaker units registered with theapertures of said baffle, and a common amplifier substantially devoid ofinterior obstructions for all of said units.

8. In a device of the character described, a fiat apertured baffle, aseries of loud-speaker units registered with the apertures of saidbafiie, and a common amplifier substantially devoid of interiorobstructions for all of said units.

9. In a device of the character described, a baliie having a series ofapertures arranged substantially in a line, a series of sound generatingunits registered with the apertures of said baiiie, and a trough-shapedamplifier substantially devoid of interior obstructions extendingforwardly of said baffle.

10. In a device of the characterfdescribed, a flat baiflle having aseries of apertures arranged in a substantially straight line, a seriesof sound' generating units registered with the apertures of said baffle,and a troughshaped amplifier substantially devoid of interiorobstructions extending forwardly of said baille.

11. In a device of the character described, the combination of a seriesof sound-producing units and a trough-shaped amplifier which flares fromsaid units to the outlet thereof for amplifying the sound generated byall of said units, said amplifier being adapted to produce asubstantially cylindrical wave front and being substantially devoid ofinterior obstructions.

12. In a device of the character described, the combination of a seriesof sound-producing units and a trough-shaped amplifier for amplifyingthe sound generated by all of said units, said amplifier being adaptedto produce a substantially cylindrical wave front, and said amplifierflaring from said units to the outlet thereof to minimize refiectionfrom adjacent sound reflecting surfaces and being substantially devoidof interior obstructions.

13. In combination, a plurality of soundproducing devices linearlydisposed and a common amplifier which flares outwardly from said devicesfor amplifying the sound produced by all of said devices, the interiorof said amplifier presenting uninterrupted sound-paths between thesound-producing i devices whereby each serves to impose a load on theother devices.

14. Sound amplifying apparatus including a horn flared upon two sides,the rear edges of the two sides being substantially paraliel, a spacingstrip provided with a plurality of openings therethrough disposedbetween the parallel edges, a plurality of loudspeakers, one for eachopening, said loudspeakers being adapted to be operated simultaneouslyto produce a wide smooth fan of sound waves.

l5. A loudspeaker comprising a member having a nonvibrating planesurface, and a plurality of sound radiating bodies mounted on saidmember for simultaneous operation.

16. A loudspeaker comprising a member having a nonvibrating surface, anda plurality of sound radiating diapliragms substantially mounted invertical alignment on said member, said sound radiating diaphragms beingpositioned so that the direction of motion of each is substantiallyperpendicular to the line of vertical alignment.

17. A loudspeaker comprising al non vibratory baffle member and aplurality of vibratory elements carried by said member and arrangedsubstantially one above the other, said vibratory elements beingpositioned to radiate sound waves substantially at right angles to thevertical axis of said baffle member.

18. A loudspeaker comprising a member having a non-vibrating planesurface, and a plurality of sound radiating bodies mounted in a singleline on said member for` .simultaneous operation.

In testimony whereof I have signed this specification.

CARLETON D. I-IAIGIS.

